Risk Factors of Renal Involvement Based on Different Manifestations in Patients with Ankylosing Spondylitis.

BACKGROUND/AIMS: Renal involvement is one of the most common extra-articular complications caused by ankylosing spondylitis (AS). Most studies have focused on the incidence rate, clinical manifestation and pathology, while risk factors have hardly been investigated. Therefore, the objective of this study was to assess the risk factors of renal involvement in patients with AS.

METHODS

Clinical and biochemical data of 926 AS patients were collected. Based on the manifestations of renal involvement, patients were divided into three groups and the differences in clinical and biochemical characteristics were compared. A group with non-renal involvement served as a control. Multivariable logistic regression was used for analyzing risk factors of renal involvement in AS.

RESULTS

Of the 926 AS patients, 201 patients suffered from renal involvement. Moreover, female AS patients faced a higher risk of hematuria compared to male patients. As indicated by the data obtained from multivariate logistic regression analysis, gender, uric acid (UA), immunoglobulin A (IgA), and serum albumin (ALB) were found to be risk factors of renal involvement in AS. An increase in UA or IgA levels, or a decrease in ALB level can increase the risk of renal involvement with multiple manifestations (more than one manifestation of renal damage). According to our findings, no definite variable was identified as a risk factor of proteinuria in AS patients.

CONCLUSION

In AS patients, UA, IgA, and ALB levels can indicate the risk of renal involvement in AS patient and need to be paid special attention. Furthermore, women are subjected to a higher risk of hematuria.